We take a look at what we need, how to store and more...

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How much water do we really need?

The body is about 60% water, give or take.  We’re constantly losing water from our bodies, primarily via urine and sweat.  There are many different opinions on how much water we should be drinking every day.  Most health authorities commonly recommend eight 8-ounce glasses, which equals about 2 liters, or half a gallon.  This is called the 8×8 rule and is very easy to remember.  However, there are other health gurus who think we’re always on the brink of dehydration and that we need to sip on water constantly throughout the day… even when we’re not thirsty.  

Can More Water Increase Energy Levels and Improve Brain Function?

sailing the atlantic water and

Many people claim that if we don’t stay hydrated throughout the day, our energy levels and brain function can start to suffer.   There are actually plenty of studies to support this.

In one study in women, a fluid loss of 1.36% after exercise did impair both mood and concentration, while increasing the frequency of headaches.

There are other studies showing that mild dehydration (1-3% of body weight) caused by exercise or heat can negatively affect many other aspects of brain function.

However, keep in mind that just 1% of body weight is actually a fairly significant amount. This happens primarily when you’re sweating a lot, such as during exercise or high heat.

Mild dehydration can also negatively affect physical performance, leading to reduced endurance.


water and dehydration sailing the

Dehydration is one of the most common preventable medical conditions in the world. Yet for something so common, most of us are unaware of its dangers. Here are a few things you might not know about dehydration:

1. 75 Percent of Americans Are Chronically Dehydrated. A survey of 3,003 Americans found that 75 percent likely had a net fluid loss, resulting in chronic dehydration. Although the survey found that Americans drank about eight servings of hydrating beverages per day, this is offset by drinking caffeinated beverages and alcohol and eating a diet high in sodium.

2. Dehydration Causes Fatigue. A pair of recent studies found that young people who were mildly dehydrated were much more likely to feel fatigued  during moderate exercise and even when sedentary. Unsurprisingly, fatigue is a common dehydration symptom, and it’s said to be the No. 1 cause of midday fatigue.

3. Thirst Means You’re Dehydrated. Dehydration triggers the body’s thirst response. So when you feel thirsty, dehydration is already setting in. In many experiments, just 1 to 2 percent dehydration has been shown to trigger thirst . This level of dehydration can happen quickly, especially following intense exercise or when battling viruses.

4. Dehydration Causes Foggy Memory, Irritability, and More. Dehydration, even mild dehydration, has been shown to put stress on our cognitive functioning. In younger adults, for instance, dehydration was linked to a dip in concentration and short-term memory, as well as an increase in feelings of anxiety and irritability. With children, studies are more conclusive that hydration can improve attention and memory.

5. Hydration Can Boost Your Metabolism. Although the evidence is limited, your metabolism could benefit from drinking cold water. In fact, one study found that drinking cold water helped boost healthy men and women’s metabolic rate by 30 percent.  The researchers concluded that the body expended more energy heating the cold water, which resulted in the boost in metabolism.

What is over-hydration?

over hydration sailing the atlantic canary island sailing
          and cruising guides

All of the major systems of your body depend on water to work properly. Drinking adequate amounts of water helps your body:

Most people, especially those who exercise in hot weather, are more concerned about not drinking enough water. However, drinking too much water can also be dangerous.

Over-hydration can lead to water intoxication. This occurs when the amount of salt and other electrolytes in your body become too diluted. Hyponatremia is a condition in which sodium (salt) levels become dangerously low. This is the main concern of over-hydration.

If your electrolytes drop too low too quickly, it can be fatal. Death by over-hydration is rare, but it can happen.

Are there different types of over-hydration?

Increased water intake

This occurs when you drink more water than your kidneys can remove in your urine. This can cause too much water to collect in your bloodstream.

Retaining water

This occurs when your body can’t get rid of water properly. Several medical conditions can cause your body to retain water. 

Both of these types are dangerous because they throw off the balance between water and sodium in your blood.

What causes over-hydration?

Over-hydration is an imbalance of fluids. It happens when your body takes in or holds on to more fluid than your kidneys can remove.

Drinking too much water or not having a way to remove it can cause water levels to build up. This dilutes important substances in your blood. Endurance athletes, such as those who run marathons and triathlons, sometimes drink too much water before and during an event.

It’s also important to remember that water needs vary with age, sex, weather, activity level, and overall health. So there is no exact formula on how much to drink. Common situations such as extreme heat, significant activity, and illness with fever will all require more fluid intake than average.

In a healthy person, your urine is a good indicator of your hydration status. Pale yellow urine that looks like lemonade is a good goal. Darker urine means you need more water. Colorless urine means you are over-hydrated.

Some conditions and medicines cause overhydration by making your body hold on to more fluid. These include:

Other conditions and drugs can cause increased water intake by making you extremely thirsty. These include:

Water Conservation

Even with a water maker it is important to conserve water on-board.  From the obvious not letting the tap run whilst brushing teeth or washing hands, to collecting every drop that comes out of the sky. 

Install a sea water tap.  so long as you are in a clean anchorage, or on passage  then use this for washing up, also washing hands etc, to rinse your dishes fill a spay bottle with water, or just a cup of water to rinse will normally do.

When in islands where water is an issue (particularly Cape Verde and the Canary Islands - don't worry about the Azores they have more than they know what to do with!), or usually comes from big desalination plants, be frugal, if in a marina, don't leave your hose running, try not to wash the boat too often, the locals will appreciate your efforts to conserve one of their precious resources.

Water catchers

There are many different ways to catch water, from a simple tarp to plugs for your gunwhale drain holes.  Biminis make excellent water catchers - use an ordinary hose fitting in the lowest part of your bimini.

hose fitting sailing the atlantic canary
            island sailing guides

When it rains simply attach a hose to it and fill your tank(s) - yes it really is that simple.

If you have side curtains on your bimini, fold up the edge to create a gutter, this can be drained directly into tanks or other recepticles. O course any water collected in your dinghy is perfect to use for washing or rinsing clothes.  If you are seriously low on water, but not sure about its cleanliness, or you are out and about, then think about getting a mini water filter straw.

Water makers

spectra venture 200 water maker sailing
          the atlantic canary island sailing and cruising guides

If you're lucky enough to have one - great, if not, this is a big investment, but worthwhile if you intend upon long passages or being at anchor for any length of time. 

There are many different makes, but Spectra really is the leader in this game.  Their Ventura 200T "...is the same size and configuration as the Ventura 150, but uses a higher displacement Clark Pump to produce more water. This allows it to operate in warm waters above 50F (10C), delivering over 8 gallons (31 liters) per hour. With it’s modular design, it’s an ideal system for installation in tight spaces whether you’re cruising, fishing, or racing. Simple analog controls and gauges display the feed water pressure and the product flow meter. A hand-held salinity monitor and a three-way valve for product water testing are included."  Spectra make many different models, also hand water makers which are perfect for lefe rafts and grab bags, click here for their website.  (This is an independent review of spectra water makers - after 13 years of ownership and no problems).

A couple of survival methods for making fresh water

Papaswamp lives on an island, here's their method of making drinking (potable) water.

And here are a few other ideas...

Get a large pot with a lid and an empty drinking cup. The glass should be big enough to hold a fair amount of fresh water.

Slowly pour some salt water into the pot. Do not overfill.

  • Stop well before the water level has reached the mouth of the glass.

  • This will make sure no salt water splashes into the glass while boiling.

  • You don't want to get any salt water into the drinking glass, or your newly made fresh water will be contaminated.

Place the pot, cover upside down on the pot. This will allow the water vapor as it condenses to drip into the drinking glass.

Bring the water to a slow boil. You will want to boil the water slowly over low heat.

  • A violent full boil can contaminate the drinking water by splashing into the glass.

  • Too much heat can cause a glass to break.

  • If the water is boiling quickly and violently, the glass may shift away from the center of the pot and the handle of the pot lid.

Watch the pot as the water condenses. When water boils, it becomes pure vapour, leaving behind anything that was dissolved in it.

  • As the water becomes vapour, it condenses in the air as steam and on the cover's surface as water droplets.

  • The droplets then run down to the lowest point (the handle) and drip right into the glass.

  • This will probably take 20 minutes or more.

Should the worst happen...

and you've found yourself marooned

Find your life raft and any other debris. You can use parts of your life raft to construct a system for making fresh water from sea water. 

  • This method is most helpful if you are stranded on a beach with no fresh water.

  • It was developed by stranded pilot during WWII in the Pacific.

Find the gas bottle from your life raft. Open it and fill it with sea water. 

  • Filter the sea water through a cloth so you don't get too much sand or other debris in the water.

  • Don't fill the bottle up too much. You will want to avoid spilling the water out the top of the bottle.

Find the hose and leak stoppers from the life raft. Attach the hose to one end of the leak stoppers.

    • This will provide a tube for fresh condensed water vapor to travel out of the bottle of sea water as its heated.

    • Make sure the hose is free of kinks or clogs.

    • See that the seal between the hose and leak stoppers is strong. This will help you to avoid any fresh water leaking out of the hose

Plug up the top of the gas bottle with the leak stoppers. Use the opposite end of the leak stoppers from where you've attached the hose.

Build a bank of sand and bury the hose. This will keep the hose steady as fresh water travels through it.

  • Keep the end of the hose exposed. This is where fresh water will trickle out.

  • Don't bury the gas bottle or leak stoppers. You will need to have this exposed to keep watch to make sure there are no leaks.

  • Make sure the hose is relatively straight and free of kinks as you bury it.

  • Place a pan underneath the exposed end of the hose. This will collect water the fresh water.

Make a fire and place the gas bottle directly above the flame. This will boil the salt water in the bottle. 

  • As the water boils, steam will condense in the top of the gas bottle and travel into the hose as fresh water.

  • As most of the water boils, the condensed steam will travel through the hose and into the pan.

  • The water collected in the pan will be desalinated and safe to drink.


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